Work out your own salvation?

Philippians 2:12 says 'work out your own salvation...with fear..for it is God what works within you'. Loosely paraphrased...

So, what does that mean for us? I hear a lot of talk about Tolle and the greatness of the Presence of Now. Is that not just the Kingdom of God within us? What about this working out salvation on your own? If Jesus died for us, for our salvation, then why do we have to work on it?